Friday, October 15, 2010

TVA has Big Plans for the Future

TVA is conducting a comprehensive study of resource options to meet the region’s needs for electricity and to help achieve environmental sustainability for the next 20 years. This Integrated Resource Plan or IRP is called TVA’s Environmental and Energy Future. The draft plan is available for public comment.

The Integrated Resource Plan (IRP) Baseline need for additional generating capacity, or energy efficiency and demand response (EEDR), programs is 9,600MW in 2019 and growing to 15,500MW in 2029.

New generation:
1.     Coal
Note:  (TVA currently operates 59 coal fired generating units at 11 generation plants with a total capacity of 14,500MW)
Two configurations of new supercritical pulverized coal (SCPC) plants are considered in the IRP evaluation:
a.     Single-unit 800-MW SCPC plant with carbon capture and storage (CCS)
b.    Two-unit 1600-MW SCPC plant with CCS

2.     Natural gas
Note: (TVA has 87 combustion turbines (CT) at nine power plants, with a combined generating capacity of approximately 6,000 MW)
a.     The IRP evaluation includes both simple and combined cycle natural gas fueled options. In a simple cycle unit, natural gas is used in the fueling of combustion turbines, where it is combusted with air at high pressure and temperature, then expanded to drive a shaft

3.     Nuclear
Note: (The capacity of TVA’s existing nuclear units is 6,900 MW, which includes three reactors at TVA’s Browns Ferry Nuclear Plant, two at Sequoyah Nuclear Plant, and one at Watts Bar Nuclear Plant)
a.     On August 1, 2007, the TVA Board approved the completion of the 1150 MW Unit 2 at the Watts Bar Nuclear Plant. The project is included as a current resource in TVA’s generating portfolio and is scheduled for completion in the fall of 2012.
b.    TVA has included Bellefonte Units 1 and 2 as well as Units 3 and 4 in the IRP evaluation. In addition to the four Bellefonte units, a non-site specific option based on the Advanced Passive 1000 reactor is also included in the IRP.
                                          i.    Located at the Bellefonte site in northeast Alabama, Bellefonte Units 1 and 2 are the two partially completed Babcock and Wilcox (B&W) pressurized light water reactors with a capacity of 1,260 MW each.
                                         ii.    In October 2007, TVA submitted a Combined Construction and Operating License Application to the NRC for two new Westinghouse Electric Co. designed Advanced Passive 1000 reactors. These reactors are to be located at the Bellefonte site and designated as Bellefonte Units 3 and 4 to demonstrate the feasibility of NRC’s then new combined construction and operation licensing process.

Thursday, October 7, 2010

Solar Energy Plants Planned for California--Does It Make Sense?

Two large solar plants were approved Tuesday for construction on federal lands.  Department of Interior (DOI) post.  See analysis of the proposed plants below the position statements.

Position Statements:
1. Solar thermal is more cost effective than PV solar.
2. Construction per kW is extremely high while operating expenses are low for solar installation relative to other sources of energy generation.
3. Capacity factor for solar is 18-25% and therefore is useful for peak power only.  Given the high cost of construction it is not a generation source which can offset current baseline power generation methods (Coal, Hydro, Nuclear).  It can offset peaking power provided by gas turbine and diesel generation. If it is to be used for sustainable power than it must be supplemented with other generation sources to cover the low capacity factor.
4. Do projects like these make business or financial sense?  If the goal is to have renewable generation at any expense than yes.  If the goal is to reduce dependence on CO2 emitting baseline power generation (Coal, gas turbine, diesel, natural gas) than I submit there are more efficient and cost effective ways.

5. The large footprint of solar and wind generation requires remote siting and challenges with energy transmission.
6. A carbon tax and solar efficiency gains coupled with a transmission network will be required to make solar cost competitive.

Proposed Projects
The projects approved will employ two different types of solar energy technology. The Imperial Valley Solar Project, proposed by Tessera Solar of Texas, will use Stirling Energy System's SunCatcher technology on 6,360 acres of public lands in Imperial County, California. The plant is expected to produce up to 709 megawatts from 28,360 solar dishes, enough to power 212,700 – 531,750 homes (my note: 20% of the time). Estimated cost $2.1 Billion. The initial installation will include 300MW. The rest would require a new line, like San Diego Gas & Electric’s 123-mile proposed Sunrise Powerlink, which has been approved but faces challenges in federal and state courts.

The Chevron Lucerne Valley Solar Project, proposed by Chevron Energy Solutions of California, will employ photo-voltaic solar technology on 422 acres of public lands in San Bernardino County, California, and will produce up to 45 megawatts from 40,500 solar panels, enough to power 13,500 – 33,750 homes (my note: 20% of the time).

Let's break down the various technologies that will be used:

Tessera Solar and the Stirling Energy System SunCatcher
The SunCatcher is a 25 kWe solar dish that automatically tracks the sun.  It collects and focuses solar energy on a power conversion unit which is a closed loop high efficiency four cylinder reciprocating solar Stirling engine.  Closed loop in that it uses an internal working fluid that is recycled through the engine.  The solar energy heats and pressurizes the fluid and turns the Stirling engine. 

A generator is connected to the Solar Stirling Engine; this generator produces the grid-quality electrical output of the SunCatcher. Waste heat from the engine is transferred to the ambient air via a radiator system similar to those used in automobiles. The gas is cooled by a radiator system and is continually recycled within the engine during the power cycle. The conversion process does not consume water, as is required by most thermal-powered generating systems. Data and picture Source.